1. Field of the Invention
The present invention relates to an authentication system for instruction processing apparatuses equipped with authentication means for executing user authentication at the time of using instruction processing apparatuses such as image forming apparatuses. It also relates to an image forming apparatus, an authentication control method and an authentication control program for use in the authentication system.
2. Description of the Related Art
The following description sets forth the inventor's knowledge of related art and problems therein and should not be construed as an admission of knowledge in the prior art.
In recent instruction processing apparatuses, such as MFPs (Multi Function Peripherals), for use in companies or offices, it has become popular to provide authentication functions. This arises from the necessity of strengthening user administration so as to protect the securities of MFPs since a number of users input, output or store images in MFPs and also to prevent a harmful influence to external terminals due to user's invalid operations since MFPs are connected to external terminals via a network to exchange images.
A method for realizing such authentication function is known. In this method, authorized user information is registered in an apparatus main body in advance like a department administration and the user information is compared with user information inputted at the time of using the apparatus.
In this method, however, the authentication can be performed only at the apparatus. Under the circumstances, in recent years, it becomes common to connect an authentication server to these apparatuses via a network so that authentication can be performed at any image forming apparatus installed in offices. In this system, the authentication server authenticates when a user such as an employee uses a MFP and the like, and authorization for the use of the apparatus is issued to the user within authorized limits on a plurality of functions of the MFP when the authentication is established.
Conventionally, as disclosed in Japanese Unexamined Laid-open Patent Publication No. 2001-312380, another technique is known. According to the technique, for example, a print restriction server is connected to a printer which is an instruction processing apparatus via a network so that the print restriction server performs user authentication. As a result of the user authentication, if it is recognized that the user is a registered user, the server transfers the print job and the server address to the printer so that the printer allows the printing when the obtained server address coincides with a registered server address.
In the technique disclosed in the aforementioned publication, however, in cases where the user authentication cannot be performed due to an error, such as a network failure, occurred between the printer and the authentication server (print restriction server), there is a problem that the printer cannot be used even if the user is an authorized user.
Authentication via an authentication server enables detailed user restrictions against complicated high-performance instruction processing apparatuses such as MFPs. Therefore, as for a function of transmitting image data to an outside connected to a network, e.g., a function of transmitting image data after scanning an original document, it is possible to restrict the data amount and/or destination in detail every user. However, for a user who uses the apparatus to make a small amount of copies, although strict security protection and/or copy number administration are not necessary, the user is required to access the authentication server every time the user uses the apparatus, which makes the user to feel bothersome.
The description herein of advantages and disadvantages of various features, embodiments, methods, and apparatus disclosed in other publications is in no way intended to limit the present invention. Indeed, certain features of the invention may be capable of overcoming certain disadvantages, while still retaining some or all of the features, embodiments, methods, and apparatus disclosed therein.